The rope supporting the chandelier is badly damaged (a DC 30 Perception check recognizes this). There is a 20% chance each time a PC walks under it that the rope snaps.

If an enemy is aware of the PCs, it knows that the chandelier is perfect to drop on the characters. If the enemy can, he casts grease on the floor immediately beneath it, which imposes a –2 penalty on Reflex saves to avoid being crushed, and waits for PCs to walk under it before gnawing through the last strands of rope.